content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
   *  contributor license agreements.  See the NOTICE file distributed with
   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You under the Apache License, Version 2.0
   *  (the "License"); you may not use this file except in compliance with
   *  the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  
  /**
  * @author Alexey V. Varlamov, Stepan M. Mishura
  */
  
  package android.org.apache.harmony.security.asn1;
  
  import android.org.apache.harmony.security.internal.nls.Messages;
  
  /**
   * Represents ASN.1 bit string value
   * 
   * @see http://asn1.elibel.tm.fr/en/standards/index.htm
   */
  
  public final class BitString {
  
      private static final byte[] SET_MASK = { (byte) 128, 64, 32, 16, 8, 4, 2, 1 };
  
      private static final byte[] RESET_MASK = { 0x7f, (byte) 0xbf, (byte) 0xdf,
              (byte) 0xef, (byte) 0xf7, (byte) 0xfb, (byte) 0xfd, (byte) 0xfe, };
  
      /**
       * Sequence of bits padded with unused bits.
       * @see #unusedBits 
       */
      public final byte[] bytes;
  
      /**
       * Number of unused bits in the last byte.
       */
      public final int unusedBits;
  
      /**
       * Constructs bit string
       * 
       * @param bytes - array of bytes that represents bit string,
       *                including unused bits
       * @param unusedBits - number of unused bits
       * @throws IllegalArgumentException - if parameters are invalid
       */
      public BitString(byte[] bytes, int unusedBits) {
  
          // constraints are set according X.690
          if (unusedBits < 0 || unusedBits > 7) {
              throw new IllegalArgumentException(
                      Messages.getString("security.13D")); //$NON-NLS-1$
          }
  
          if (bytes.length == 0 && unusedBits != 0) {
              throw new IllegalArgumentException(
                      Messages.getString("security.13E")); //$NON-NLS-1$
          }
  
          this.bytes = bytes;
          this.unusedBits = unusedBits;
      }
  
      /**
       * Constructs bit string from array of booleans
       * 
       * @param values - array of booleans
       */
      public BitString(boolean[] values) {
          unusedBits = values.length % 8;
          int size = values.length / 8;
          if (unusedBits != 0) {
              size++;
          }
          bytes = new byte[size];
          for (int i = 0; i < values.length; i++) {
              setBit(i, values[i]);
          }
      }
  
      public boolean getBit(int bit) {
          int offset = bit % 8;
          int index = bit / 8;
          return (bytes[index] & SET_MASK[offset]) != 0;
      }
  
      public void setBit(int bit, boolean value) {
          int offset = bit % 8;
          int index = bit / 8;
          if (value) {
              bytes[index] |= SET_MASK[offset];
          } else {
              bytes[index] &= RESET_MASK[offset];
          }
      }
  
      public boolean[] toBooleanArray() {
          boolean[] result = new boolean[bytes.length * 8 - unusedBits];
          for (int i = 0; i < result.length; i++) {
              result[i] = getBit(i);
          }
          return result;
      }
  }